Long-term, large-current operation of superconducting power transmission that carried five million passengers

The application of superconducting power transmission to electric railway systems demonstrates its potential to reduce electrical losses typically observed in urban rail networks. Building on this concept, we developed a practical railway power supply system incorporating superconducting cables to deliver electrical energy from substations to trains. Using this system, more than 61,000 train services were operated, collectively transporting approximately five million passengers. The superconducting power transmission system provided a stable electricity supply over more than 1 year of continuous operation on a suburban line in Shizuoka. A further demonstration was conducted on an urban commuter line in Tokyo where multiple long trains operate simultaneously. Currents of up to 4500 A were supplied from a substation to accelerate commercial trains. The results confirmed that the superconducting feeding system maintained stable operation throughout the day, even under the highly variable load conditions characteristic of metropolitan areas, and reliably supplied power to commercial trains.